GB1062907A - Improvements relating to the control of data tape movement - Google Patents

Abstract

1,062,907. Statistical apparatus. STANDARD TELEPHONES & CABLES Ltd. July 24, 1964, No. 29758/64. Heading G4C and G4M. Each of a series of groups of digits is recorded together with one of a series of regularly repeated characteristics, and on read-out of the digit groups, means is responsive to an interruption or disorder in the regular series of characteristics to indicate a malfunction in the read-out process. The digit groups may be recorded, for example, on paper or magnetic tape, or in a ferrite core store. The Figure shows a tape in which each digit group is punched in tracks 3-7 in 2-out-of-5 code, and alternate digit groups have an additional hole punched in track 8. In reading such a tape, a bi-stable circuit is switched between its two states as successive digit groups are read, and its state is compared with the output of a device sensing track 8, an unequal comparison signifying a read-out error, due for example to one digit group being omitted or read twice. An alternative method of detecting read-out errors is to record alternate odd and even parity bits with successive digit groups, and to check that successive digit groups read from the store have opposite parity.